148 or 125?

Depends on the timeframe. I model the 1920s so I'm using code 125 for the main and code 100 for the spurs. I may switch to code 83 for the spurs and save the 100 for the yard.

You are coming from 3-rail?  Stick with .148 track and .172 wheels.

I have been in 2-rail for 70 years, machine my own drivers and main frames, and I have lousy luck with fine scale wheels and track.

However, if you are truly a careful modeler and an accomplished machinist, you can go with finer scale track and wheels, all the way to Proto-48 and still be successful.  If you are an average modeler, stick with the tried and true components to avoid frustration.

I like 125 for main lines, 100 for yards.

Take this with the proverbial grain of salt since I'm coming from the 3-rail side of the house, but if I were starting over and in 2-rail AND hand-laying track, I'd probably go with Code 125 on the mainlines and Code 100 for the spur tracks and yard. Height wise, you'd be looking at 6" rail height for the Code 125 and about 5" for the Code 100.

I have some older O scale 2 rail  from the 40's and some have a deep flange , I chose 148 for the main line and 125 for side tracks.   The 148 will handle most all wheels including the major brands of toy trains, weathered on scale ties it looks fine, with out having to turn down flanges. electrical is not an issue, as I am converting to dead rail

The Pennsy mainline rail weight ranged between 132 and 152 lb.  I picked code 148, which corresponds to a height of 7.10".  That is close enough to the 7  5/16 " height of 140 lb rail

Ralph,

Model rail code refers to the height of the rail. If you measure the rail, Code 100 is .100 inch high, Code 125 is .125 of an inch...

Prototype rail can be different from different manufacturers. I've linked to a document from the ATSF which list various manufacturers of rail and the sizes based on the weight of the rail. There are cases in here that different weights of rail had the same heights.

http://www.shamokindivision.co...nsions-of-rail-1.pdf

The PRR Mainlines were heavy rail as mentioned above.    So Code 148 would represent that well.    I would use code 125 for sidings.    I'd be tempted to try code 100 on industrial track, but not sure.    I do have some older steamers and the flanges may be just big enough to hit the heads of some spikes if not totally tight down.    I have had no issues at all with code 125.   My yard and ladder tracks are all code 125.

@prrjim posted:

The PRR Mainlines were heavy rail as mentioned above.    So Code 148 would represent that well.    I would use code 125 for sidings.    I'd be tempted to try code 100 on industrial track, but not sure.    I do have some older steamers and the flanges may be just big enough to hit the heads of some spikes if not totally tight down.    I have had no issues at all with code 125.   My yard and ladder tracks are all code 125.

So, how do you transition from 148 to 125 or any other step-down situation?

Shims...?

Mark in Oregon

@adferraro posted:

Depends on the timeframe. I model the 1920s so I'm using code 125 for the main and code 100 for the spurs. I may switch to code 83 for the spurs and save the 100 for the yard.

Wow...code 83. That's getting pretty small. I think that's more or less the "standard" now for HO. Would like to see some pictures, if and when you do that. 👍

Mark in Oregon

@bob2 posted:

You are coming from 3-rail?  Stick with .148 track and .172 wheels.

I have been in 2-rail for 70 years, machine my own drivers and main frames, and I have lousy luck with fine scale wheels and track.

However, if you are truly a careful modeler and an accomplished machinist, you can go with finer scale track and wheels, all the way to Proto-48 and still be successful.  If you are an average modeler, stick with the tried and true components to avoid frustration.

This is an important point for me. I want to be sure that I'm not restricted to run locos and cars to the point where it becomes difficult to find stuff to run on my layout. It seems that .148 provides the best opportunity.

Yes, I'm coming from 3-rail (and HO).

@Strummer posted:

Wow...code 83. That's getting pretty small. I think that's more or less the "standard" now for HO. Would like to see some pictures, if and when you do that. 👍

Mark in Oregon

Yeah, even code 100 is used in HO.

Something to consider is that the wheel treads are a bit wider and the flanges a bit larger on the models. Those proportions will make the smaller rails look even smaller. Most are not using 115 treads and truly scale flanges. Once the track is ballasted and the rails are painted and weathered, the rails really don't jump out at you like they do when they are not painted.

The Pennsylvania modelers I know who are building layouts are using code 148 for their heavy mainline traffic.

Another consideration is our 5 foot gauge track.  Most cannot see it, but I perceive our track as being too wide for our models.  Smaller rail exacerbates that illusion.

O Scale rail code equivalencies to HO rail:

148 in O is equal to code 83 in HO or 132-140 pound rail (probably the most common modern mainline rail)

125 in O is equal to Code 70 in HO or about 100-110 pound rail (most common on secondary trackage or sidings)

100 in O is equal to code 55 in HO or about 75-80 pound rail (suitable for little used spurs or early 20th century secondary trackage)

83 in O is equal to code 46 in HO or about 60 pound rail

Here's a picture of my first module. The main is code 125 as mentioned and the spur is code 100. All handlaid.

Wheel profiles are .145 and nothing hits the spike heads. It tracks well too so far.

I'm not sure yet about the code 83, but I think it's worth testing out.

@Jim Scorse posted:

O Scale rail code equivalencies to HO rail:

148 in O is equal to code 83 in HO or 132-140 pound rail (probably the most common modern mainline rail)

125 in O is equal to Code 70 in HO or about 100-110 pound rail (most common on secondary trackage or sidings)

100 in O is equal to code 55 in HO or about 75-80 pound rail (suitable for little used spurs or early 20th century secondary trackage)

83 in O is equal to code 46 in HO or about 60 pound rail

Thanks, Jim. This is a great guide.

@adferraro posted:

Here's a picture of my first module. The main is code 125 as mentioned and the spur is code 100. All handlaid.

Wheel profiles are .145 and nothing hits the spike heads. It tracks well too so far.

I'm not sure yet about the code 83, but I think it's worth testing out.

Very nicley done. Are you using nickel-silver rail?

@bob2 posted:

Another consideration is our 5 foot gauge track.  Most cannot see it, but I perceive our track as being too wide for our models.  Smaller rail exacerbates that illusion.

Scale track gauge is 4 feet 8 1/2 inches, which is 3 1/2 inches narrower than 5 foot gauge. Can one actually see that 3 1/2 inches when scaled down to O Scale, i.e. 1/4 inch to the foot?  Wouldn't that be less than 1/16th of an inch?

@Jim Scorse posted:

O Scale rail code equivalencies to HO rail:

148 in O is equal to code 83 in HO or 132-140 pound rail (probably the most common modern mainline rail)

125 in O is equal to Code 70 in HO or about 100-110 pound rail (most common on secondary trackage or sidings)

100 in O is equal to code 55 in HO or about 75-80 pound rail (suitable for little used spurs or early 20th century secondary trackage)

83 in O is equal to code 46 in HO or about 60 pound rail

Something is off with that table. Those conversions are off.  Not by much, but they are all off

O Scale 1/48 scale

HO Scale 1/87 scale

Ratio is 87/48 = 1.813

Now look at the conversions

148/83 = 1.783

125/70 = 1.786

100/55 = 1.818

83/46 = 1.804

They all should be 1.813

The numbers are not even consistent!  The biggest error is only 1.7%, But still, the math ain't THAT hard

What is also off is the equivalece, There is no range of heights for a given weight.  There is a direct relation between code and rail weight. As I said in my post above, 140 lb rail corresponds to 7  5/16" high which is Code 151 in O scale.

Man, that is a lot of repeated photos!  We really need to get rid of that "reply with quote" button.  But nice photos the first time they were posted.

Hot - the human eye is a remarkable instrument.  Coupled with our ability to synthesize, we can see such minor dimensional errors.  We can also not see them if we so desire.  I solve the problem both by using .148 rail and by modeling in 17/64 scale.  My original alternative was 1 1/8" gauge.

Like those who truly like the looks of the center rail, I like the hefty look of .172 wheel treads.  They are wildly incorrect, as is our gauge, but I choose to ignore that.  Most 2-railers choose to overlook the wide gauge, and thus they do not see it.  Nothing wrong with that.

@John Sethian posted:

Something is off with that table.

What is also off is the equivalece,

Also the spelling... 😁

Mark in Oregon

@John Sethian posted:

Something is off with that table. Those conversions are off.  Not by much, but they are all off

There is no range of heights for a given weight.

I failed to mention these are rough equivalencies to *AVAILABLE* rail in HO.

Depending on the rail section (RE,DY, CB etc) Rails of the same weight can measure differently in height, web, base and head.

The American Society of Civil Engineeers shows 90 pound rail can have heights of 5-3/8" and 5-5/8".

The ARA shows heights of 5-41/64 and 6" for 100 pound rail and 5-17/64 for 90 pound

AREA shows 136 and 140 pound rails have the same height of 7-5/16

If you put current 5ft O Scale nest to Proto-48, you probably can see the difference in track gauge and the narrower wheelsets and flanges.    However, if you just use plain old O scale by itself it looks pretty good.    Also the difference between Proto-48 and 5 ft O scale is not nearly as obvious as between 3 rail and 5ft. 

With Proto-48, to get the full affect, you need to use narrower truck bolsters and narrower truck sideframes to show the obvious proto-48 look.

Unless you want to do a lot of conversion and scratchbuilding, you probably don't want to do Proto-48.    Proto-48 is certainly more accurate in the track and and wheels, but there is not much available RTR.    Also, steamers would require very significant skill to convert. 

Standard O Scale requires relatively the same precision that HO does.    This is more that required for 3 rail, but less than Proto-48.

As for transition from different rail heights, say 125-148   It is relatively easy.    The way I do it is to use the larger rail 148 size joiner.   I cut a small strip of brass that is the same width as the base of the smaller 125 rail and maybe half inch long - can be longer or shorter.     For this transition a strip, 023 inches thick by probably 3/32 or .093.    Width does not matter as long as less than or equal to the base of the rail.     .023 thick is not so common, but .022 is usually available in the brass strip racks in hobby shops and will work fine I think.    Solder this strip to the underside of the base of the smaller 125 rail to make it the same height at the joint as the code 148.     Then slide the smaller rail into the rail joiner and the top should match the top of the coder 148.    You may be using only one size rail joiner.

I use Code 125 for my main line (still meant to only be a secondary main) and Code 100 for my spurs. "American Switch & Signal" do cast nickel-silver transition joint bars for where the two codes meet, seen here in my first photo.

The beauty of hand spiking track is the ability to replicate some of the rough track seen on the more notorious Short Lines.

Work such as ballasting is still under way on my layout. And yes I realise that strictly speaking the main & siding in the above photos are the wrong way round, the main should be next to the Depot, but due to the curves on my layout - down to 36" radius - I gave the main the wider curve beyond the Depot.